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Software Engineer, Windows (VPN)

Proton
Backend Developer • On-site • Full-time • 📍 Barcelona +1
📄 View original listing (EN)

Proton, founded in 2014 by CERN scientists, builds privacy-first products used by millions. As an engineer on the small Windows VPN team, you would design, build, maintain and evolve Proton's Windows applications across the entire application lifecycle. The codebase is primarily written in .NET and WinUI (C#/XAML), with cross-platform logical core libraries written in Rust, and software quality is central to the role.

Stack

C#GitGitLab.NETRust

Responsibilities

  • ▹Design, build, maintain and evolve Proton's applications on Windows across the entire application lifecycle
  • ▹Handle feature design and implementation, CI/CD configuration, deployment, monitoring and operational incident response
  • ▹Collaborate closely with product managers and engineers across the company
  • ▹Help define, maintain and improve the testing stack, including unit tests, integration tests and automated GUI tests using FlaUI

Requirements

  • ▹Strong experience in C# and .NET development
  • ▹Strong experience building and maintaining Windows desktop applications using frameworks such as WinUI, WPF or similar
  • ▹Solid understanding of MVVM architecture, dependency injection, asynchronous programming (async/await) and event-based messaging patterns
  • ▹Proven ability to write maintainable, well-tested and scalable codebases
  • ▹Demonstrated experience driving change within an organization and leading complex technical projects
  • ▹Strong understanding of software architecture and engineering best practices
  • ▹An appreciation for user experience and design quality
  • ▹Working knowledge of networking fundamentals (TCP/IP, DNS, routing concepts) and an interest in VPN technologies and protocols
  • ▹Experience with code debugging, profiling and performance optimization on Windows
  • ▹Familiarity with Git-based workflows, CI/CD pipelines (GitLab) and modern collaborative development practices
  • ▹Experience with gradual rollout and observability tooling (telemetry, metrics, monitoring and alerting)

Nice to have

  • ▹Rust experience

Soft skills

Ability to drive change within an organizationAppreciation for user experience and design qualityCollaboration with product managers and engineers

What we offer

  • ▹Office-first setup with offices in Geneva, Zurich, Prague, Barcelona, Paris, London, Vilnius, Skopje and Taipei, plus up to 30% work from home
  • ▹All devices and software needed for the role
  • ▹Lunch and snacks at the office
  • ▹Transport cost support (public transport, bike allowance or parking)
  • ▹Stock options when you join
  • ▹Flexible working hours
  • ▹Learning and development opportunities, including training, conferences and events
  • ▹Comprehensive health insurance, retirement savings options, generous leave and wellness programs

About the company

Proton was founded in 2014 by scientists from CERN on the belief that privacy is a fundamental human right. It runs the world's largest encrypted email service and a suite of privacy tools, is profitable and independent with no VC control, and has 500+ team members across 50+ countries.